Interpretive Summary: The University of California, Riverside, Department of Plant Pathology operates the California Citrus Clonal Protection Program (CCPP). The CCPP introduces new varieties into California for use by the California citrus industry, and also sanitizes varieties already in California. As the final part of the process, the new varieties undergo a rigorous "Variety Introduction" (VI) disease testing and therapy program. Varieties that successfully complete the VI process are free of all graft-transmissible diseases and are eligible for quarantine release and subsequent availability to growers, nurseries, researchers, and others. These available varieties are identified within the California citrus industry with unique "VI identification" numbers. In some cases, little information about CCPP VI introductions is readily available to the general public. As a result, the CCPP, the UC Riverside Citrus Variety Collection, and the USA-ARS National Clonal Germplasm Repository for Citrus and Dates have compiled information on the 18 most recently released and distributed varieties. This information is presented in a popular article aimed at growers and nurseries.

Technical Abstract:
The Citrus Clonal Protection Program (CCPP) is operated through the Department of Plant Pathology and Microbiology at University of California (UC) Riverside and is funded in large part by The California Citrus Research Board (CRB). The CCPP processes citrus propagative material in two phases. First, during the quarantine phase, citrus budwood of potentially important commercial varieties is introduced from any citricultural area, germplasm or breeding program of the world under the authority of a permit which is issued to CCPP by the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service in cooperation with the California Department of Food and Agriculture (CDF A). While in quarantine at the Rubidoux Facility in Riverside, newly imported varieties are tested extensively and any detected pathogens (such as viruses and bacteria that cause the tristeza, exocortis, stubborn, or Huanglongbing-HLB disease of citrus) are eliminated via therapy. The second phase includes the production of bud wood source trees which are moved out of quarantine in Riverside and to the UC Lindcove Research and Extension Center (LREC) in Exeter, California, where the CCPP Protected Foundation (screenhouse) and Evaluation Blocks (field) are housed. Trees established in the Evaluation Blocks are evaluated for trueness to type by scientists, growers, and nurserymen and are accessible to the public during field and fruit testing days (aka "walkthroughs"). Trees established in the Protected Foundation Blocks are off limits to the public, they are regularly tested for a variety of pathogens and are registered with the CDF A as budwood source trees.
Over the past several years, many varieties have been through the rigorous "Variety Introduction-VI" disease testing and therapy program under quarantine at the CCPP. Varieties that successfully complete the VI process receive a unique VI identification number that permanently accompanies the budwood that is made available to growers, nurseries, researchers, and others. Little information about many of the CCPP VI varieties is accessible to the public, or may take a great deal of effort to find: As a result, the UCR-Citrus Variety Collection (CVC), USDA-National Clonal Germplasm Repository for Citrus and Dates (NCGRCD), and CCPP, have compiled information on the 18 most recently distributed varieties.